M.Sc. (Med.), Faculty of Health Sciences, University of the Witwatersrand, 2004Endemic circulation of hepatitis E virus (HEV) in Namibia was suspected from
serological data during an outbreak of non-A non-B hepatitis in Rundu, in 1995. The
source of the outbreak was surmised to be the water supply, which had been
compromised approximately six months earlier. This study examines nucleotide and
amino acid sequence data obtained from the open reading frame 2 (ORF2) region towards
the carboxy terminal end (3’-end) of the HEV genome extracted from the stool of
Namibian patients infected during this outbreak. The overall aim is to establish a
polymerase chain reaction (PCR) for molecular diagnosis of HEV, to isolate HEV from
specimens collected from acute viral hepatitis outbreaks such as this one in Namibia, to
characterize, at the genomic level, the strain of the virus involved, to compare the strain
to those involved in other outbreaks of HEV in southern Africa and to relate this
information to available data from other parts of the world. A nested reverse
transcriptase-polymerase chain reaction (RT-PCR) was developed for molecular
diagnosis of HEV and four representative HEV isolates from this outbreak have been
successfully amplified, sequenced and analysed over a 451 base pair (bp) region of a
subgenomic fragment from the 3’-end of the genome in ORF2. Phylogenetic analysis
showed the four Namibian HEV isolates clustered with a Mexican isolate in genotype II
and shared a 85.8-86.3 percent (%) nucleotide identity with the 1987 Mexican isolate but
were only 77.6-79.6 % similar to other African isolates. HEV isolated from the same
region of Namibia in 1983 was reported to cluster into genotype I and this analysis
clearly indicates the difference between the strains involved in the two outbreaks. Virus
from sporadic cases of HEV isolated in 1997/8 in Nigeria were also found to be from
genotype II. This is the first study performed in South Africa to isolate, amplify by PCR and sequence the HEV. It is also the first to characterize HEV as the causative agent of
the hepatitis outbreak that occurred in Namibia in 1995. As it reports the presence of a
second unique HEV strain in southern Africa, we conclude that HEV genotypes may be
more widely distributed than previously thought
